geomagField.hpp File Reference

Data Structures
struct	GeomagMainField
	Structure for variables related to the International Geomagnetic Reference Field 13th Generation International Geomagnetic Reference Field Schmidt semi-normalised spherical harmonic coefficients, degree n=1,13 in units nanoTesla for IGRF and definitive DGRF main-field models (degree n=1,8 nanoTesla/year for secular variation (SV)) More...
struct	GeomagSecularVariation
	Structure for secular variation (SV) inherited from GeomagMainField. More...

Functions
void	readIGRF (string filename)
	Read the IGRF file Only support the latest generations of IGRF file from IGRF-11.
double	decimalYear (GTime time)
	Convert time to decimal year For example: 2019-07-18 00:00:00 -> 2019.54247.
bool	getSHCoef (GTime time, GeomagMainField &igrfMF)
	Calculate the SH coefficients at given epoch based on a piecewise linear model For years starting in 1900 and ending in 2020, the change rates should be calculated using the two nearest data points For the final 5 years of model validity (2020 to 2025 for IGRF-13), the Secular Variation coefficients are explicitly provided See ref [1].
VectorEnu	getGeomagIntensity (GTime time, const VectorPos &pos)
	Compute the geomagnetic field components in geocentric local reference system at given time and position See ref [1] [2] Note that the normalisation of associated Legendre functions for Geomagnetic field is different from that for Geogravitational field, i.e.
VectorEcef	getGeomagIntensityEcef (GTime time, const VectorPos &pos)
	Compute the geomagnetic field components in ECEF reference system at given time and position.

Function Documentation

decimalYear()

double decimalYear

(

GTime

time

)

Convert time to decimal year For example: 2019-07-18 00:00:00 -> 2019.54247.

Parameters

time

time

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getGeomagIntensity()

VectorEnu getGeomagIntensity	(	GTime	time,
		const VectorPos &	pos )

Compute the geomagnetic field components in geocentric local reference system at given time and position See ref [1] [2] Note that the normalisation of associated Legendre functions for Geomagnetic field is different from that for Geogravitational field, i.e.

Pnm_gra_norm(x) = sqrt((2-dm0)*(2*n+1) * (n-m)/(n+m)) * Pnm(x) Pnm_mag_norm(x) = sqrt((2-dm0)* (n-m)/(n+m)) * Pnm(x) where dm0 is the Kronecker delta which is equal to 1 for m==0 and 0 for m!=0 Thus we have Pnm_gra_norm(x) = sqrt(2*n+1) * Pnm_mag_norm(x) See ref [3] [4]

Parameters

time	time of geomagnetic field to model
pos	position in geocentric spherical coordinates where geomagnetic field to model

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getGeomagIntensityEcef()

VectorEcef getGeomagIntensityEcef	(	GTime	time,
		const VectorPos &	pos )

Compute the geomagnetic field components in ECEF reference system at given time and position.

Parameters

time	time of geomagnetic field to model
pos	position in geocentric spherical coordinates where geomagnetic field to model

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getSHCoef()

bool getSHCoef	(	GTime	time,
		GeomagMainField &	igrfMF )

Calculate the SH coefficients at given epoch based on a piecewise linear model For years starting in 1900 and ending in 2020, the change rates should be calculated using the two nearest data points For the final 5 years of model validity (2020 to 2025 for IGRF-13), the Secular Variation coefficients are explicitly provided See ref [1].

Parameters

time	time of IGRF coefficients to calculate
igrfMF	map of the IGRF coefficients calculated

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readIGRF()

void readIGRF

(

string

filename

)

Read the IGRF file Only support the latest generations of IGRF file from IGRF-11.

Parameters

filename

IGRF file to read

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